IIT JEE , AIEEE Forum - Physics , Mechanics

sanjbabbar

How can we judge that a force is conservative or not without experiments???

elessar_iitkgp

Start from rest.
Keep applying the force and move in a closed path.
If the force is conservative, it won't do any work & by work energy theorem, there will not be any change in KE. So when you reach the starting point your particle will again be at rest.

If this doesn't happen, the force in non conservative.

a_buddy4uin06

The expt can b done as Elessar said...
FOR eg;
we can take in d case of throwin a body up... wen it comes down(no air resistance).... the body ll hav d same velocity with which it was projected...
anothr idea is..
WEN THE BODY IS THROWN UP THE WORKDONE IS MGH, N WEN IT COMES DOWN THE WORK DONE IS -MGH, THUS D TOTAL WORK DONE IS 0...
the above is in d case of conservtive...

NOW IN CASE Of NON-CONSERVATIVE,
lets consider friction, wen a body moves to d riy frm a to b by x units, friction will be -fx and even wen it moves frm b to a it ll be -fx... thus d net workdone is -2fx.. n not zero.. thus d definition workdone by a non-conservative force in a round trip is not zero...
to xplain this without a expt is hard.. i think..

a5hw1n_5

Also another way of detecting a conservative force is when a body executes an ossilatory motion where the total mechanical energy is conserved, then all of the forces on it should be conservative. Apply it to any example.

krishna.gopal

All these are experiments and i feel that we can't find whether a force is conservative or not without experiment

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